QUANTITATIVE ANALYSIS OF DENGUE-2 VIRUS RNA DURING THE EXTRINSIC INCUBATION PERIOD IN INDIVIDUAL AEDES AEGYPTI

Understanding the ability of the chikungunya virus (CHIKV) to be transmitted by Aedes vectors in the Americas is critical for assessing epidemiological risk. One element that must be considered is the minimum infectious dose of virus that can lead to transmission following the extrinsic incubation period. This study aimed to determine the minimum infection rate for the two Aedes species studied. The results revealed that doses as low as 3.9 log10 plaque-forming units per mL (pfu/mL) of an Asian genotype CHIKV strain can lead to transmission by Ae. albopictus, and doses of at least 5.3 log10 pfu/mL from the same strain are needed for transmission from Ae. aegypti. These low infecting doses suggest that infected individuals may be infectious for almost the entire period of their viremia, and therefore, to prevent further cases, measures should be taken to prevent them from getting bitten by mosquitoes during this period.

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The Extrinsic Incubation Period of Zika Virus in Florida Mosquitoes Aedes aegypti and Ae. albopictus

Pathogens ◽

10.3390/pathogens10101252 ◽

2021 ◽

Vol 10 (10) ◽

pp. 1252

Author(s):

Rebecca A. Zimler ◽

Barry W. Alto

Keyword(s):

Aedes Aegypti ◽

Incubation Period ◽

Health Risks ◽

Zika Virus ◽

Mosquito Vectors ◽

Zikv Infection ◽

Infected Blood ◽

Extrinsic Incubation Period ◽

Asian Lineage ◽

Blood Meals

The Asian genotype of Zika virus (ZIKV) emerged in Brazil in 2015 and subsequently spread throughout the Americas. In July 2016, Florida experienced its first locally acquired ZIKV infection in the continental U.S. Concerns about health risks from ZIKV infection have increased the need to investigate the interactions between potential mosquito vectors and ZIKV. The time it takes for an arbovirus to propagate within a mosquito, and become transmissible, is the extrinsic incubation period (EIP). The EIP for potential mosquito vectors in Florida is unknown. To address this gap in the understanding of ZIKV epidemiology, Florida Aedes aegypti (L.) and Ae. albopictus (Skuse) were orally exposed to ZIKV infected blood meals and fully engorged mosquitoes were held at a constant temperature of 28 °C through the duration of the experiment. Saliva expectorates were collected from cohorts of mosquitoes and tested for the presence of ZIKV at three-day intervals over a period of 24 days to allow for an evaluation of the EIP of the emergent Asian lineage of ZIKV. High rates of infected bodies in Ae. albopictus (75–94%) and Ae. aegypti (68–86%) were observed throughout the incubation period, which did not differ by species. Higher rates of disseminated infection were observed later during the incubation period but did not differ between species. We calculated the 50% EIP to be shorter in Ae. albopictus than Ae. aegypti (16.2 and 18.2 days post infection, respectively). The competence for ZIKV observed in both species may contribute to high rates of ZIKV transmission in Florida populations.

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Vector survival and parasite infection: the effect of Wuchereria bancrofti on its vector Culex quinquefasciatus

Parasitology ◽

10.1017/s0031182004005153 ◽

2004 ◽

Vol 129 (1) ◽

pp. 43-50 ◽

Cited By ~ 11

Author(s):

K. KRISHNAMOORTHY ◽

S. SUBRAMANIAN ◽

G. J. VAN OORTMARSSEN ◽

J. D. F. HABBEMA ◽

P. K. DAS

Keyword(s):

Incubation Period ◽

Culex Quinquefasciatus ◽

Geometric Mean ◽

Wuchereria Bancrofti ◽

Parasite Load ◽

Infected Mosquito ◽

Parasite Development ◽

Mosquito Vector ◽

Extrinsic Incubation Period ◽

Parasite Loss

This paper investigates a cohort of 2187 laboratory reared Culex quinquefasciatus fed on 69 human volunteers, including 59 persons with different levels of Wuchereria bancrofti microfilariae and 10 without microfilaria. Mosquitoes were followed until death. Mosquito survival was analysed in relation to the level of microfilaria in the human and larval count in the dead mosquito. Vector mortality during the extrinsic incubation period (12 days post-engorgement) was significantly higher in mosquitoes fed on microfilaraemic volunteers (50%) than in those fed on amicrofilaraemics (29%). Both the percentage infected and the geometric mean parasite density was significantly higher among mosquitoes which died before 13 days (45% infected and 10 larvae per infected mosquito) than those surviving beyond 13 days (39% and 2·2), suggesting a parasite loss of more than 80% during the extrinsic incubation period. A large proportion (62%) of the mosquitoes that died during the early of phase of parasite development were infected (36% in low, 26% in medium and 90% in high human Mf-density). Survival analysis showed that the parasite load in mosquitoes and the human Mf-density for a given parasite load are independent risk factors of vector survival. Overall, the hazard of dying was found to be 11–15 times higher among mosquitoes fed on microfilaraemic volunteers than those fed on amicrofilaraemics. The hazard doubles for every increase of about 60–70 parasites in the vector. As a consequence of the parasite-induced reduction in vector survival, the transmission success of the parasite is reduced. The implication of the results on control/elimination of lymphatic filariasis using mass-drug administration is discussed.

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STUDIES ON PLASMODIUM VIVAX. 2. THE INFLUENCE OF TEMPERATURE ON THE DURATION OF THE EXTRINSIC INCUBATION PERIOD*

American Journal of Epidemiology ◽

10.1093/oxfordjournals.aje.a117892 ◽

1932 ◽

Vol 16 (3) ◽

pp. 851-853 ◽

Cited By ~ 2

Author(s):

MARK F. BOYD

Keyword(s):

Plasmodium Vivax ◽

Incubation Period ◽

Influence Of Temperature ◽

Extrinsic Incubation Period ◽

Influence Of Temperature On

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Extrinsic Incubation Period (EIP)

Encyclopedia of Parasitology ◽

10.1007/978-3-662-43978-4_1145 ◽

2016 ◽

pp. 974-974

Author(s):

Heinz Mehlhorn

Keyword(s):

Incubation Period ◽

Extrinsic Incubation Period

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Cocirculation of two dengue virus serotypes in individual and pooled samples of Aedes aegypti and Aedes albopictus larvae

Revista da Sociedade Brasileira de Medicina Tropical ◽

10.1590/s0037-86822011000100023 ◽

2011 ◽

Vol 44 (1) ◽

pp. 103-105 ◽

Cited By ~ 20

Author(s):

José Eduardo Marques Pessanha ◽

Waleska Teixeira Caiaffa ◽

Alzira Batista Cecilio ◽

Felipe Campos de Melo Iani ◽

Simone Costa Araujo ◽

...

Keyword(s):

Aedes Aegypti ◽

Dengue Virus ◽

Clinical Presentation ◽

Rt Pcr ◽

Virus Rna ◽

Dengue Virus Serotypes ◽

Belo Horizonte ◽

The City ◽

Pooled Samples ◽

Virological Surveillance

INTRODUCTION: To detect dengue virus, eggs of Aedes sp were collected in the city of Belo Horizonte, Brazil, in 2007. METHODS: Egg samples were subsequently hatched and the larvae were tested for the presence of dengue virus RNA by RT-PCR. RESULTS: Among the Aedes aegypti larvae samples, 163 (37.4%) out of 435 were positive, including 32 (10.9%) of 293 individual larvae samples concomitantly positive for two serotypes. CONCLUSIONS: Virological surveillance detecting coinfected vectors in the field could represent an important strategy for understanding the numerous factors involved in the transmission and clinical presentation of dengue.

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